One prior art process of making an article from a piezoelectric powder includes the steps of mixing the powder with a few weight percent of a binder, often in a liquid solvent, to form a slip; drying the slip to remove the solvent and to form loose powder agglomerates containing dry binder; pressing the agglomerates to form disks composed of powder particles held together by the binder; and heat treating the disks to initially burn out the binder at a lower temperature and then to grow crystallites or crystals at a higher temperature. Porosity of fully heat-treated or sintered disks is usually below 5%.
The disadvantage of this prior art process is that the disks thus formed are difficult to make in large sizes.